The purpose of this study is to compare via continuous pH monitoring the effect of head of bed elevation, cisapride, and the combination of the two, on supine gastroesophageal acid reflux in a standardized, placebo-controlled, double blind manner. The results will help to elucidate the relative therapeutic roles for the two treatment modalities and better identify cost effective treatment strategies in the clinical therapy of gastroesophageal reflux disease (GERD).